Hannah Dixon, 29, used a little known banking trick called an “indemnity claim” where customers can ask their bank to claim back cash though the Direct Debit guarantee.

Later that month, Scottish Power was fined £18million by Ofgem, the energy regulator, after it found the energy firm had failed to treat customers fairly when dealing with billing issues and complaints.

In April, Scottish Power was fined £18million by OfgemCredit:
Andrew Paterson / Alamy

On other occasions we reported on implausibly huge bills including the case of one reader who received a bill for £50,000. The real bill was a fraction of that sum.

"Accurate bills are essential if consumers stand any hope of taking control of their energy use and spend. Recent upgrades by some suppliers to billing systems have resulted in teething problems, but today's figures show there's still more for the industry to do.”

Ms Osborne also advised customers to check bills carefully and speak to their supplier immediately if they think that they’ve been short changed.

Energy customers should also always provide up to date meter readings to avoid estimated bills, and check that the figure they provided has been used.

A Department of Energy and Climate Change spokeswoman said: "We are on the side of bill-payers and it is our number one priority to ensure bills are kept as low as possible for families and businesses. But the real power is in the hands of the British people.

"If bill-payers are concerned about the deal they are getting from their supplier, we urge them to join the millions of others who are switching and saving.”

Have you had an unexpected bill? Do you have a problem with your energy supplier? Tell us your story by emailing: tara.evans@telegraph.co.uk